(a)  
An operational test at the JETT M2 M3 SPS control card (fuel system card file, M7852) which uses the built in test (BIT) capability to do a check of these jettison system items: 1) fuel jettison single point sensor (SPS) 2) control card 3) wiring between the card and sensors.

 (b)  
A CMCS initiated ground test which makes sure the SPS system operates correctly for these systems: 1) fuel jettison SPS system 2) reserve tank fuel transfer SPS system

 B.
References

 (1)  
AMM 24-22-00/201, Manual Control

 (2)  
AMM 28-22-16/401, Fuel System Card File

 (3)  
AMM 31-61-00/501, Integrated Display System (IDS)

 (4)  
AMM 32-09-02/201, Air/Ground Relays

 (5)  
AMM 34-61-02/401, Control Display Unit

 (6)  
AMM 45-10-00/501, Central Maintenance Computer (CMC)

 (7)  
SSM 28-44-01

 (8)  
WDM 26-44-11, WDM 28-44-12

 C.
Access

 (1)  
Location Zones 115 Area Between Nose Gear Well and Fuselage, Left 221 Control Cabin, Left 222 Control Cabin, Right 521 Leading Edge to Front Spar, Left 621 Leading Edge to Front Spar, Right

 D.
Preconditions

 S 865-068
 (1)  
These conditions are necessary for this task:

 (a)  
Fuel Jettison SPS system serviceable.

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 (b)  
A specific quantity of fuel is necessary for this task. (The SPS sensors must be dry - not covered with fuel or wet -covered with fuel)

 (c)  
Electrical Power On (AMM 24-22-00/201).

 (d)  
Fuel System Card File is Serviceable (AMM 28-22-16/401).

 (e)  
Integrated Display System (IDS) serviceable (AMM 31-61-00/501).

 (f)  
Airplane must be in the ground mode (AMM/31-61-00/501).

 (g)  
CDU installed (AMM 34-61-02/401).

 (h)  
Central Maintenance Computer (CMC) serviceable.

 E.
Prepare for the Test

 S 865-045
 (1)  
Supply electrical power (AMM 24-22-00/201).

 S 865-046

 (2)  
Make sure these circuit breakers are closed:

 (a)  
P6, Main Power Distribution Panel
 1) 6F6, FUEL SYS MGMT CH1
 2) 6F8, FUEL SYS MGMT CH2

 S 865-047
 (3)  
Make sure the airplane is in the ground mode (the airplane is not jacked and the targets are not installed).

 F.
Single-Point Sensor Control Card Initiated Test Procedure

 S 865-048
 (1)  
Find the fuel quantity in the No. 2 and 3 main fuel tank.

 (a)  
Use one of the systems:
 1) The P42 refuel control panel indicators
 2) The EICAS FUEL synoptic display
 3) The fuel measuring sticks.

 S 975-049
 (2)  
Write down the fuel quantity values.

 S 865-050

 (3)  
Find the card A4 (JETT M2 M3 SPS) installed in the fuel system card file, M7852.

 NOTE: Access to the card file is in the left crawlway adjacent
____
 to the nose wheel well.

 S 745-051
 (4)  
Look at the LED indicator light for CH1, on card A4.

 (a)  
The green light will show if the fuel level in the No. 2 main tank is below the single point sensor (the sensor is dry).

 (b)  
The green light will not show if the fuel level in the No. 2 main wing tank is above the single point sensor (the sensor is wet).

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A
747-400 MAINTENANCE MANUAL
　
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